The rate is usually greater than 120 bpm with broad QRS complexes.
VT may be monomorphic (typically regular rhythm originating from a single focus with identical or similar QRS complexes) or polymorphic (may be irregular rhythm, with beat to beat variation in QRS complexes).
Monomorphic VT is the most common form of sustained VT.
Non-sustained VT is defined as a run of tachycardia of less than 30 seconds' duration; a longer duration is described as sustained VT.